ML19295B679
| ML19295B679 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/19/1980 |
| From: | Ballard R Office of Nuclear Reactor Regulation |
| To: | Clark R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19248B746 | List: |
| References | |
| FOIA-81-362 NUDOCS 8010090547 | |
| Download: ML19295B679 (6) | |
Text
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s EWIORY DOMT G0?Y SEP 191980 MEMORANDUM FOR: Robert A. Clark, Chief Operating Reactor Branch No. 3 FROM:
Ronald L. Ballard, Chief Environmental Engineering Branch, DE
SUBJECT:
EVALUATION OF PROPOSED PROCEDURES FOR THE ERADICATION AND CONTROL OF CORBICL1.A SP. INHABITING THE CONTAINME'iT COOLING UNITS AT ANO-2 As requested by L. Engle on September 17, 1980, Dr. M. Masnik of the Aquatic Resources Section has reviewed the proposed program for the eradication and control of Corbicula sp., the Asiatic Clam, inhabiting the containment cooling units (CCU) at Arkansas Nuclear One Unit 2.
General coments pertaining to the licenseets sutnittal of September 16, 1980 that were informally transmitted in draft fem to L. Engle on September 18, 1980 are also attached.
Based on the September 16, 1980, submittal from the licensee and subsequent telephone discussions with the licensee on September 18, 1980, we understand that the program for eradication includes heat treatment and flushing operations of the CCU. The licensee stated that piping upstream of the 10" header to the isolation valve has been flushed and as far as they can visibly inspect there are fes clams remaining in the headers. The licensee plans to heat treat the system from the isolation valve in the 10" header, downstream to ardincludinp the coolers. They stated that water at a temperature of 1300F will be used to heat the system. Flushing of the system subsequent to heat treatment will be performed.
Based on available infomation (see attachment), the heat treatment will result in 100% mortality of the molluscs. Further flow restrictions due to continued growth of the existing mollusc population will not occur. Flow recuction may occur due to possible sloughing off of individual valves from molluscs killed by heat trettment from areas not presently restricting flow, and movement of these valves io the condenser tubes. The licensee's proposed flushing sequence subsequent to ?he heat treatment but prior to station startuo should remove most of the detachec dead molluscs and lessen the possibility of blockage due to valve movement. It it reasonable to assure that decay of the molluscs will be a gradual process over a numoer of days resulting in the gradual sloughing off of valves from any molluscs remaining in the system. The licensee has telephonically connitted to monitor flow on an every other day schedule for the first 14 days of station operation to assess whether or not flow through the CCU is decreasing due to the movement of valves from dead molluscs.
If these valves restrict flow this reduction should be gradual and readily observed during the monitoring program.
&O30090 W7
Robert A. Clark The licensee has proposed a program of continuous chlorination during surveillance testing to eliminate the possibility of future infestations of Asiatic clams in the CCU. The continuous chlorination procedure will substantially reduce the introduction of live mollusc larvae but will not eliminate it entirely. As stated in the attachment, chlorination will kill non-valved larvae but will not result in mortality to valved larvae.
Based on discussions with TVA an effective method of control is continuous chlorination in conjunction with a filtering device with a seive size of 1/32" (see attachment). The filtering device will remove the valved larvae. The licensee has stated that effective control procedures resulting in complete mortality to both valved and non-valved larvae will comence subsequent to the next scheduled fuel load (next spring).
In the interim, continuous chlorination to control non-valved larvae will be perfomed during sur-ve111ance testing. Valved larvas introduced during surveillance testing between now and the next scheduled fuel load may become established in the CCU. However, it takes approximately one year to mature to a size sufficient to block condenser tubes. Therefore, no significant reduction in flow across the CCU is expected due to maturation of the valved larvae between now and when complete cleaning of the CCU is perfomed during the next fuel load.
It is recomended that the licensee submit a written report of the heat treatment program. The report should include the maximun temperature of the treatment water, duration of treatment, how temperature within the system was monitored, results of the effectiveness of pre-operational flushing program, and the results of the surveillance pmgram.
Ronald L. Ballard, Chief Environmental Engineering Branch Division of Engineering
Attachment:
As stated DISTRIBUTION cc:
R. Vollmer Docket D. Muller EEB<Rdg T. Novak RBallard R. E. Martin L. B. Engle E. Blackwood E. Imbro R. Samworth M. Masnik D
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